Surrey 240 (Stoneman 67, Burns 50, Leach 6-43, van der Merwe 4-54) and 106 for 4 drew with Somerset 429 (Clark 3-75) and 69 (Ashwin 6-27, Moriarty 4-20)
R Ashwin stepped up his preparations for India's Test series against England by taking 6 for 27 as Surrey's LV= Insurance County Championship match against Somerset ended in a draw.
The 34-year-old off-spinner, who was making a one-off appearance for Surrey, helped rattle Somerset out for 69 in their second innings with left-arm spinner Dan Moriarty picking up 4 for 20 on a Kia Oval pitch offering plenty of help to the slow bowlers.
It left Surrey needing 259 to win in 57 overs and England slow left-armer Jack Leach followed up his 6 for 43 in Surrey's first innings with another wicket but the hosts had reached 106 for 4 when the teams shook hands at 5pm with Jamie Smith 46 not out.
A day during which all but seven overs were bowled by the spinners started with Leach sealing his best figures against Surrey when he picked up last man Amar Virdi. Roelof van der Merwe had Moriarty lbw with the third ball of the day to finish with 4 for 54 as Surrey were bowled out for 240 and conceded a first innings deficit of 189.
Somerset did not enforce the follow on and Ashwin, who took just one wicket in 43 overs in the first innings, took the new ball at the pavilion end and quickly settled into a high-class spell. Although the pitch was slow, the ball turned sharply out of the footholds and Somerset's batsmen found it hard going against a world-class operator.
Ashwin took his first wicket in his fourth over when Steven Davies was drawn forward and edged behind. Tom Lammonby fell to an ill-judged sweep, James Hildreth was pinned on his stumps when Ashwin went round the wicket, George Bartlett bowled offering no shot and van der Merwe fell leg before just before lunch which Somerset reached on 60 for 7.
Ashwin took his sixth wicket with a superb delivery which drifted in and spun sharply to defeat Ben Green's defensive push. He was given excellent support by Moriarty, who bowled arguably the best delivery of the day to end Devon Conway's determined resistance with a ball that spun sharply past his defensive push and knocked back off stump.
Surrey's hopes of an unlikely victory chase effectively ended by the 13th over when they lost their third wicket. Leach had Mark Stoneman held at short leg and van der Merwe picked up Rory Burns and Ryan Patel before ending a stand of 66 for the fourth wicket when he pinned Hashim Amla to finish with match figures of 7 for 115.